1. Field of the Invention
The present invention relates to multi-ton lifting of marine platforms using spreader bars and like lifting devices. More particularly, the present invention relates to a marine lifting apparatus that utilizes a spreader bar assembly having end portions which can be removably fitted to the end of a section of a cylindrical beam or a like structural member which has been cut to a desired length. Even more particularly the present invention relates to a spreader bar apparatus having a spreader bar and end caps with transverse cylindrical lifting posts that allow direct attachment of slings thereto.
2. General Background
In the lifting of marine platforms, drilling rigs and production platform (such as for loading onto ships or for construction), a derrick normally provides a load line which branches at a bridle and attaches in two places to an elongated lifting bar or frame known in the art as a spreader bar. The spreader bar then has depending load lines lowered from it at each end which are then affixed to a piece of equipment to be lifted. This spreader bar apparatus per se and the use of spreader bars to lift items is generally known in the art.
Very large spreader frames custom constructed to fit a piece of equipment of a given load and dimension, and thus are not reused except on a piece of equipment of similar dimension and equal or lesser load.
Attempts have been made in various United Sates patents to teach a method for providing an adjustable spreader bar that can be used over a variety of spreader lengths. Some spreader bars use removable end caps to which shackles are affixed. The Khachaturian patent 4,397,493 discloses a spreader bar with removable end caps, each having openings to which shackles can be attached.
The use of multiple spreader bars as part of a lifting frame or assembly is discussed in the Khachaturian patent 4,538,849. In the '849 patent, a composite spreader frame assembly provides a primary load line having a bridle attached to the load line and four branching lines connected at one respective end to the bridle. A pair of separate elongated support bars are each supported independently by the alternate radially extending branch lines. A plurality of lifting eyes are removably connected at each respective end of the elongated support bars. Four secondary depending load lines which are generally vertical during lifting are attached at the upper end to the lifting eyes and at the lower end to a load to be lifted.
In U.S. Pat. No. 4,128,267 entitled "Lifting Beam" there can be seen a lifting beam comprising an elongate member carrying one or more pivotally mounted hooks for engagement of a load to be lifted. A balance weight is provided on the hooks to lie on either side of the pivotal axis thereof so as to cause the hook to be biased into or from engagement of the load to picked up or released when the beam is lowered onto same.
In U.S. Pat. No. 4,136,903 there can be seen a "Tire Lifting Apparatus" which comprises a master support sleeve, two moveable arms slidably associated therewith, and two hook units pivotally connected to the arms for easy engagement with the inner rim of a tire.
A "Handling Beam for Heavy Elongate Objects" can be seen in U.S. Pat. No. 3,762,756 which comprises a missile handling beam assembly readily engageable with conventional missile supporting lug arrangements. The assembly does not impose any stress on the object being handled, since a lifting hook can be located in a position closest to the center of gravity of the load, hence the attitude of the object can be easily controlled during the lifting and lowering movements.
In U.S. Pat. No. 4,258,949 entitled "Extensible Spreader Frame for Cargo Containers" there can be seen an extensible lifting spreader frame comprising a pair of oppositely extending beam arms slidably received within a central pair of side-by-side connected sleeve beams. Beam cross arms at the outer ends of the sleeve beams mount twist-lock lock latching hooks at their opposite ends for attachment to the four selected top corners of a cargo container to be lifted.
A "Sling Mounting Head" for use with a spacer element and mouthing two members of a sling chain can be seen in U.S. Pat. No. 4,215,891. The sling mounting head has a body portion including a central section, and first and second end sections extending from the central section.
In U.S. Pat. No. 3,206,243 issued to B. F. Miles on Sep. 14, 1965, there is seen a "Spreader Bar" apparatus.
U.S. Pat. No. 3,010,751 entitled "Adjustable Lift Hooks" issued on Nov. 28, 1961 to E. J. Day et al.
A "Sling Carrier" device is seen in U.S. Pat. No. 3,252,729 which issued on May 24, 1966 to R. A. Holmes.